Eric Enge posted a screen shot on Google+ of Google displaying featured snippets for queries that are site commands. It is true, it does work.
I tried it for [site:searchengineland.com what is seo] and I got a featured snippet from Search Engine Land:
Eric, as well as others, says it is new behavior for Google to show featured snippets for a site command.
Of course, this might be an easier way for SEOs to see if they do come up, at all, as featured snippets for their most important keywords. At the same time, even if the site command returns you as a featured snippet, it doesn't mean you will show for that generic (none site command) query. For example [what is seo] doesn't return Search Engine Land for me, it returns Wikipedia:
Knowing Google considers some of your content as featured snippet worthy, even if it does not show for a generic query, is good for SEOs to know.
So go at it, use the site command to see if you come up for featured snippets.
Forum discussion at Google+.
